Signature

The safety I/O configuration signature is a number that uniquely identifies the configuration of a device and verifies that the device is configured as expected by the safety application. The configuration signature consists of the following:

A signature ID that represents the I/O module configuration
The time and date that the module configuration was last applied

The signature changes according to how you Configure the Safety Input Module Delay Time.

For a controller to establish a connection to a safety I/O module, the configuration signature in the controller must match the configuration signature in the safety I/O module. The process of synchronizing the configuration signatures requires these steps:

Offline changes to the I/O module configuration change the time and date. Once altered, the time and date remain changed even if the configuration is returned to the current running configuration. Offline changes to the time and date do take effect until you deploy the safety application to the safety controller.

If a safety I/O module was previously configured in another location, the I/O module retains the configuration signature from the previous location. When a controller and a safety I/O module attempt to establish a safety connection, a mismatch of the configuration signatures can cause the connection to fail. To clear the safety I/O module configuration and enable the controller to download the module configuration to the safety I/O module, you must reset Ownership.

The controller verifies that configuration signatures match, so there is no requirement to monitor or document the configuration signature. If the configuration signature changes unexpectedly, the safety connection between the controller and I/O module fails and causes the I/O module to enter its safe state.